Hello & Welcome Pim!
I have not heard that France was a particularly tough place to be vegan... I want to visit France someday - I'd appreciate suggestions of where & what to check out when/if I do make it over there. Have ya seen this: http://happycow.net/europe/france/paris/index.html
I've never been to the USA, but I'd love to. I went to England last year, and it didn't take long for me to notice the "V" sign on food packing. We don't even have that in France. Ask for a vegetarian meal at any given place, first they'll treat you as an alien, and then they'll come back with a ham and butter sandwich. Maybe it's not the toughest place for vegan, but I don't want to know what it is.
Paris is a very touristic city, you'll have to face overcrowded sites. There is much to say. First, I know a cheap 2 stars hotel that worth 3, but as long as they don't have an extra room per floor they cannot get this 3th star. Still the sight over the north of Paris is amazing there. Then it depends on what you want to see, what you are interested in. There a lot of museum, churches, old buildings, gardens, modern useless buildings and so on. Before christmas there are lights every where (even in my district), each year they increase the number of light.
Spring is the best moment in the year. Not too crowded, good weather, good light.
There are also some interesting place in the subburbs of Paris. You can also visit other regions, full of cute small town and local products.
Feel free to ask me more about what you are interested in.
I've only been vegan for three months, so I didn't really seek for vegan restaurant, plus I'm the only vegan among my friends...
In fact I already know one place. "Le paradis du fruit" (the fruit heaven). They serve delightfull fruitjuice. I'll try one at random in the next days.
Anyway being vegan is saddly not the best way to fully enjoy french food.
Thanks everyone for your reception.